I know the "modern" stance as advised by most coach is to use a waist harness and a slightly higher boom--neck height when standing close to mast with the sail upright? But I prefer to put boom at shoulder height or just under, with a seat harness (a very low hook height) and short lines (mostly 22 inches). Short lines allow me to sail in an upright stance with the sail fully sheet in, in straps and my butt not touching water in chop. Much less spin out and better upwind.

I've tried raising the boom to see the effect but soon return to original height. With a high boom when planing in straps, I find all the weight is in the back foot and I have a feeling of pulling out of footstrap of my front foot (especially with modern slalom boards), which is very unsecured and TIRING! The board also slows down more going over chop. In terms of maneuverbility, in fact a lower boom is much better. With a lower boom, my arms are parallel to water surface so easier to push or pull the sail. Easier gybes (plane out of some for my level), duck gybes, waterstarts. In fact I fall more in gybes with a high boom. More difficult waterstart (need to stretch more to get sail upright, thus requires slightly more wind) and even uphaul (easy to fall backwards). I question whether using a waist harness is productive at all, especially one needs to raise boom height. Anyway most moves are done hook out, so does not depend what harness is put on.

I know PWA slalom guys use a high boom, but that's their setting with wider board. I personally don't sail wide boards as I don't need to or I choose to. What do you guys think? How about the wave discipline? Feel free to share.